A locking bolt in a vane-type camshaft adjuster is already known from the prior-art EP 1 371 818 A2.
A vane-type hydraulic camshaft adjuster is also known from WO 2009/114500 A1, a center-locking mechanism, in which the vane is locked in a central position, being implemented with the aid of a locking pin.
Hydraulic camshaft adjuster systems having center-locking mechanisms as well as hydraulic camshaft adjuster systems which operate according to the vane principle are thus known. They make it possible to adjust the control times of an internal combustion engine during engine operation.
When starting the engine, if the oil pressure in the engine has not yet been built up, a hydraulic camshaft adjuster must be mechanically fixed. This is necessary to prevent uncontrolled oscillation and thus a noise development. “Startup rattling” should also be mentioned in this connection, which should be stopped. An end stop locking in a so-called “RETARD” or “ADVANCE” position is standard practice here. The vane of the rotor strikes the stator. The movement in the other rotation direction is prevented by a mechanical locking element. This element may be placed axially or radially in the camshaft adjuster.
A mechanical fixing of the rotor between the two RETARD and ADVANCE end stops is rarely implemented but is being required more and more of automotive manufacturers. One speaks of a center-locking mechanism in this case. Due to the fact that few energy sources may be tapped during the center-locking process, and the initial position may be on the retard or advance side, a center-locking is much more difficult to implement than an end stop locking in the retard or advance position.